Toward the end of Phoenix’s crowd-pleasing set, out strolled none other than R&B mega-star R. Kelly, wearing a bejeweled baseball cap and motocross gear, to sing his hits “Ignition (Remix)” and “I’m a Flirt” over the band performing the melody of their own hit, 2008 single “1901” and new song “Chloroform.” (Watch video here)

While some in the crowd seemed legitimately confused at what was occurring onstage in front of them, a majority of the masses gathered for Phoenix’s set were excited by the surprising pairing, lustily singing along to R. Kelly’s lyrics.

No one appeared more excited by the proceedings than Phoenix themselves, who flashed huge grins throughout the song, with Kelly exchanging hugs with frontman Thomas Mars and guitarist Laurent Brancowitz on his way offstage.

Phoenix had knocked out a spectacular set all on their own prior to R. Kelly’s arrival, opening with anthemic new single, “Entertainment” (from their forthcoming new album, Bankrupt!, due on April 23), before launching into a singles-heavy set that also featured a grip of well-received new songs heard by most of the audience for the first time. Cruising through songs like “Fences” and of course, “Lisztomania” from their breakthrough full-length, Wolfgang Amadeus Phoenix, they also made sure to touch on older fan favorites like “Long Distance Call” and “Too Late.”

Frontman Mars left his own indelible imprint on the night, ending the show by running through the crowd and climbing atop a massive truss in the middle of the polo field before crowd-surfing his way back to the stage, all set to a rousing reprise of the set’s opening number, “Entertainment.”

Phoenix wasn’t the only Coachella act to inject a dose of pure R&B into their set. British dance-rock minimalists the xx welcomed Solange Knowles to the stage for a dynamic duet with singer/bassist Oliver Sim on late soul-pop heroine Aaliyah’s 1996 song, “Hot Like Fire.”